On some architectures NAG F90 compiler requires -Qpath option to be
predefined in F90FLAGS. configure script is not smart enough
to figure out where NAG F90's libraries/executables reside (usually
not in PATH). Besides, NAG F90 compiler is not supported.
If CFLAGS and F90FLAGS setup by ./configure script are incorrect one
may fix them directly in Makefile/makeisdc1. For instance, some people
want to have libraries compiled with debug option turned on ("-g"),
and configure script does not always put "-g" option in CFLAGS/F90FLAGS.
Please keep in mind that any subsequent run of configure script will
overwrite any changes.